“Nonadiabatic spin manipulation with adiabatic protocols”, by Xuedong Hu, ( University at Buffalo)

Wednesday, March 8, 2017 - 4:00pm
Condensed Matter Journal Club Seminars

Experimental and theoretical research on spin qubits in quantum dots have achieved significant progress over the past decade.  In particular, single confined electron spin has been demonstrated to be extremely coherent; while two-spin manipulation using exchange interaction are controllable and fast.  On the other hand, achieving faster single spin manipulation and longer distance spin communication remain daunting tasks.  Here I discuss explorations we have pursued in implementing adiabatic spin control protocols nonadiabatically.  We show that for both single-spin rotation and three-spin state transfer, when we push the adiabatic protocols very fast, they can still work, albeit only resonantly.  Specifically, in the case of single-spin control,  we find that the spin trajectory on the Bloch sphere displays some interesting propeties.  The three-spin state transfer, on the other hand, can be mapped onto the adiabatic population transfer in a three-level atom in quantum optics, or a rotating spin with S=1 in the adiabatic frame.  In short, our results show that it is possible for a spin-control protocol to be both fast and robust, and point to a potential new way to perform other quantum gates.

PAB 4-330